EP1722611B1 - Electronic device with an electrical coil - Google Patents

Abstract

The electronic device has an electric coil arranged on a component reservoir (2) and an arrangement (4-9) for carrying away heat generated by the electric coil via the component reservoir. The arrangement is designed so that the temperature of the coil while operating is reduced by at least three degrees C, especially by 5 to 10 degrees C.

Description

Technical area

The invention relates to an electronic device with an electric coil, which is arranged on a component reservoir.

State of the art

In known electronic devices, in particular electronic ballasts, which have at least one electrical coil, it is always a worthwhile goal to be able to carry out a reduction of such devices. By such an increasing miniaturization of electronic ballasts, the power-transmitting components are thermally increasingly burdened. The inductances contained in these electronic ballasts reach ever higher operating temperatures, whereby a cooling of these inductors or a heat reduction in these inductors is required in order to avoid damage or destruction of the electronic ballasts can.

It is Z. B. off DE 103 32 842 A1 (Honsberg-Riedl) known that such inductances are cooled, for example, by a potting compound. A major disadvantage of such a procedure is the associated relatively high costs. Another disadvantage of this solution is the fact that the mechanical stress of the solder joints, which can occur depending on the potting compound when passing through temperature cycles. Another alternative, thermal loads in electronic ballasts, especially in the inductors reduce or get under control, is given by attaching heat conductivities. These heat-conducting mats are designed such that they should transfer the resulting heat to nearby housing parts. This solution is associated with relatively high costs. Furthermore, the problem of mechanical stress on the solder joints also occurs here. Furthermore, it is known to cool inductors or inductors with fan devices. This solution is also relatively expensive and also has the disadvantages that a considerable noise is present and possibly a reduced life is associated.

Presentation of the invention

Therefore, it is an object of the present invention to provide an electronic device with an electric coil, in which overheating of the components can be prevented and thereby damage or destruction of the electronic device can be avoided. This object is achieved by an electronic device having the features of claim 1.

An electronic device according to the invention comprises at least one electrical coil which is arranged on a component reservoir. An essential idea of the invention is that the electronic device has means which are designed such that a heat generated by the electric coil can be derived from this electrical coil via the component reservoir. With the electronic device according to the invention can be achieved that the heat generated during operation of the electronic device, in particular during operation of the electric coil, can be dissipated in an optimized manner. By the invention, the means are designed and arranged such that a heat transfer from the coil via the component reservoir, the heat transfer can be relatively efficient, whereby overheating of the electrical coil or adjacent components can be prevented. As a result, damaged or destroyed due to overheating can be prevented even with smaller and smaller electronic devices, in which the components are arranged closer and closer to each other. In addition, can be provided by the inventive design of the electronic device, a relatively inexpensive implementation of efficient heat transport. Furthermore, a mechanical load of the solder joints can be reduced or excluded and noise, as occurs in the prior art with a fan cooling, can be avoided.

According to the invention, a first winding for the electrical function of the electric coil and at least one additional winding around the bobbin, which is designed for heat transport from the coil to the component reservoir and is without electrical function, are arranged around a bobbin. Thus, at least two windings are around the bobbin wherein one is required for the electrical function of the coil and the second is without such an electrical function and is designed only for heat transfer from the heat generated by the electrical coil in operation to the component reservoir.

Advantageously, the means for dissipating the heat are designed such that the temperature of the electric coil during operation can be reduced by at least a value of 3 ° C., in particular by a value of 5 ° C. to 10 ° C. The means are thus designed such that they preferably effect such a temperature reduction of the electrical coil or the electronic device, which prevent damage to or impairment of the operation of the electronic device during operation. In addition, these means are also designed such that they are designed with regard to an optimized temperature reduction, an optimized cost structure and an optimized space requirement.

In an advantageous embodiment, the electric coil is designed as a choke coil and a coil body of the choke coil is formed of a thermally conductive material. It can thereby be achieved that a relatively good heat transfer of the heat generated during operation of the choke coil can be made possible by the coil material itself. Advantageously, the thermal conductivity of the material of the bobbin is greater than or equal to 1W / mK. Such materials allow a relatively rapid removal of heat generated.

It can be provided that metal pins are formed at the free terminals of the electrical coil, wherein the electrical coil is mechanically connected by means of the metal pins with the component reservoir. As a result, an improved heat transfer can be achieved again and the heat from the bobbin can be better transferred to the component reservoir. The component reservoir is preferably designed as a circuit board.

It can be provided that the additional winding is arranged adjacent to the first winding around the bobbin. It can also be provided that the additional winding is arranged in addition to or instead of the adjacent arrangement to the first winding at least partially on the first winding. Thus, depending on the respective configuration of the electronic device and the electrical coil, arranging the first and the second winding can be carried out in a versatile and flexible manner, depending on the situation.

A further advantageous embodiment of the electronic device according to the invention has a heat transfer element, which is at least partially disposed about a first winding of the electric coil, wherein this first winding for the electrical function of the electric coil is required. By means of the heat transport element can thus be dissipated to the component reservoir in an efficient manner, the heat generated during operation of the electrical coil. It can be provided that the heat transfer element is at least partially formed on the first winding. As a result, on the one hand, it can be achieved that heat transport can be optimally carried out and, moreover, the smallest possible space requirement for the heat transport element is required.

It can also be provided that the heat transfer element is mechanically connected to the component reservoir, in particular with a solder joint is attached to the component reservoir. This ensures on the one hand a mechanically particularly stable arrangement and on the other hand allows a particularly effective and efficient heat transfer to the component reservoir. The heat transfer element is advantageously designed as a metal sheet.

It can further be provided that the heat transfer element has at least one cooling element which extends at least partially in the horizontal direction next to the electrical coil and is arranged at a distance from the component reservoir.

In an advantageous embodiment, the electronic device according to the invention is designed as an electronic ballast, which is designed in particular for lamps, in particular for fluorescent lamps.

Brief description of the drawings

Figur 1

eine Schnittdarstellung durch ein erstes Ausführungsbeispiel eines erfindungsgemäßen elektronischen Geräts; und

Figur 2

eine Schnittdarstellung eines zweiten Ausführungsbeispiels eines erfindungsgemäßen elektronischen Geräts.

Embodiments of the invention are explained in more detail below with reference to schematic drawings. Show it:

FIG. 1

a sectional view through a first embodiment of an electronic device according to the invention; and

FIG. 2

a sectional view of a second embodiment of an electronic device according to the invention.

Preferred embodiment of the invention

In the figures, identical or functionally identical elements are provided with the same reference numerals.

In FIG. 1 is a cross-sectional view of a first embodiment of an electronic device according to the invention shown. The electronic device is formed in this embodiment as an electronic ballast 1 for fluorescent lamps. The electronic ballast 1 is arranged on a in the embodiment designed as a board 2 component reservoir. The electronic ballast 1 has a choke coil, which in the exemplary embodiment has a bobbin 3, which is arranged on the upper side 21 of the circuit board 2. The bobbin 3 is formed in the embodiment of a thermally conductive material having a thermal conductivity of at least 1 W / mK. As further from the representation in FIG. 1 can be seen, the free terminals of the choke coil are provided with metal pins 4 and 5, which protrude through recesses in the circuit board 2 and on the bottom 22 of the board 2 by means of solder joints 4a and 5a are mechanically fixedly connected to the board 2. In this regard, the bobbin 3 is firmly connected to the board 2.

As further from the representation in FIG. 1 can be seen, the bobbin 3 and the choke coil is at least partially surrounded by an element 6, which is formed in the embodiment of ferrite. The electronic ballast 1 or the choke coil comprises a first winding, not shown, which is required for the operating principle of the choke coil. This first winding thus has an electrical function. Furthermore, the choke coil comprises at least one second winding 7, which is wound around the bobbin and is designed as an additional winding. This additional winding or second winding 7 has no electrical function and serves to dissipate heat generated during operation of the inductor to the board 2. The additional winding or the second winding 7 may be wound around the bobbin adjacent to the first winding. However, it can also be provided that the second winding 7 is arranged in addition to or instead of an adjacent arrangement to the first winding at least partially on the first winding.

For optimized heat transfer from the choke coil to the board 2 is in the embodiment according to FIG. 1 further arranged as a sheet metal heat transfer element 8a arranged. As can be seen from the cross-sectional illustration, the heat transport element 8a is arranged like a hood around the second winding 7 and at least partially around the bobbin 3 of the choke coil. The heat transfer element 8a is thus at least partially integrally formed on the second winding 7. As in FIG. 1 can be seen, the heat transport element 8a is passed with its free ends through recesses in the board 2 and attached to the bottom 22 of the board 2 with solder joints 8a and 8b. As from the illustration in FIG. 1 can be seen, the free ends of the heat transfer element 8 are bent and oriented substantially parallel to the bottom 22 of the board 2. These two bent regions are oriented such that they are formed facing each other.

With the in FIG. 1 shown embodiment of the invention, an optimized heat transfer in the electronic ballast 1 can be achieved. In this regard, it should be noted that in the embodiment according to FIG. 1 several alternatives of means according to the invention for heat transfer from the inductor to the board are formed. These means comprise in the embodiment in FIG. 1 on the one hand from a thermally conductive material existing bobbin 3, moreover provided with metal pins 4 and 5 free connections of the choke coil, as well as other alternatives, the second winding 7 and the heat transport element 8. It should be noted that each of these four alternatives by itself already improved and inventive heat transfer from the Throttle towards the board 2 allows. Furthermore, it should be noted that the inventive means for heat transfer from the choke coil to the board 2 by any combination of the embodiment according to FIG. 1 said four alternatives according to the invention can be made possible. As already mentioned, in this regard each alternative alone can already realize the inventive concept. In addition, any combination of two but also three of the embodiment according to FIG. 1 trained alternatives may be provided in an electronic ballast 1. For example, it may be provided in this regard that the bobbin 3 is made of a thermally conductive material and as a second alternative, only one heat transport element 8 is arranged. However, it can also be provided that the bobbin 3 with metal pins 4 and 5 has provided free terminals and further arranged a trained without electrical function second winding 7 for heat transfer. Other combinations can be found in the FIG. 1 realized four alternatives are generated.

In FIG. 2 is shown in a cross-sectional view of a second embodiment of an electronic device according to the invention with an electric coil. Also in this embodiment, the electronic device is designed as an electronic ballast 1. In the in FIG. 2 In the embodiment shown, the electronic ballast 1 has a heat transport element 9. In contrast to the heat transport element 8 according to FIG. 1 this heat transport element 9 has no mechanical connection with the circuit board 2. As from the illustration in FIG. 2 can be seen, the heat transfer element 9 extends above the second winding 7 and the bobbin 3 and the ferrite 6. The heat transfer element 9 is formed only in the central region in the upper region of the second winding 7 to the second winding 7. The heat transfer element 9 has a first cooling element 91 and a second cooling element 92 on the side of the choke coil or of the bobbin 3 and of the ferrite element 6. The cooling elements 91 and 92 are serrated in their cross-sectional representation. The cooling elements 91 and 92 allow heat transfer from the bobbin 3 to the environment. Thereby can be achieved that in addition to the heat transfer from the bobbin 3 and the choke coil to the board 2, a heat transfer from the choke coil or from the bobbin 3 via the heat transport element 9 and the cooling elements 91 and 92 takes place to the environment.

Also in the embodiment according to FIG. 2 It should be noted that any combination of the alternatives for optimized heat transfer away from the electrical coil can be realized.

By the invention it can be achieved that the temperature of the electric coil or the choke coil of the electronic ballast 1 in operation by a value of 3 ° C to 12 ° C, in particular by a value of 5 ° C to 10 ° C can be reduced , Such a temperature reduction is optimal in two respects, because the means are designed such that they allow a cost-effective and space-saving implementation for a temperature reduction of the electrical coil or the electronic device and on the other hand, the temperature reduction takes place substantially to such a value that a Overheating and thus damaging or destroying the components of the electronic device and thus the electronic device itself can be prevented.

Claims (11)

1. Electronic device having an electrical coil, which is arranged on a component reservoir (2), the electronic device having means (4, 5; 7; 8; 9, 91, 92) which are designed such that heat generated by the electrical coil can be conducted away from the electrical coil via the component reservoir, the electrical coil having a coil former (3), around which a first winding is arranged for the electrical function of the electrical coil, the electrical coil being characterized in that at least one additional winding (7) is arranged around the coil former (3), which additional winding (7) is designed for heat transfer from the electrical coil to the component reservoir (2) and has no electrical function, the coil former (3) being made from a thermally conductive material.
2. Electronic device according to Claim 1, characterized in that the electrical coil is an induction coil.
3. Electronic device according to Claim 2, characterized in that the thermal conductivity of the material of the coil former (3) is greater than or equal to 1 W/mK.
4. Electronic device according to one of the preceding claims, characterized in that metal pins (4, 5) are formed at the free connections of the electrical coil, the electrical coil being mechanically connected to the component reservoir (2) by means of the metal pins (4, 5).
5. Electronic device according to one of the preceding claims, characterized in that the additional winding (7) is arranged adjacent to the first winding and/or at least partially on the first winding.
6. Electronic device according to one of the preceding claims, characterized in that a heat-transfer element (8; 9) is arranged at least partially around a first winding of the electrical coil.
7. Electronic device according to Claim 6, characterized in that the heat-transfer element (8; 9) is at least partially integrally formed on the first winding.
8. Electronic device according to Claim 6 or 7, characterized in that the heat-transfer element (8; 9) is mechanically connected to the component reservoir (2), in particular is fixed to the component reservoir (2) by means of a soldered joint (8a, 8b).
9. Electronic device according to one of Claims 6 to 8, characterized in that the heat-transfer element (8; 9) is in the form of a metal sheet.
10. Electronic device according to Claim 6 or 7, characterized in that the heat-transfer element (8; 9) has at least one cooling element (91, 92), which extends at least partially in the horizontal direction adjacent to the electrical coil and is arranged such that it is spaced apart from the component reservoir (2).
11. Electronic device according to one of the preceding claims, characterized in that the electronic device is an electronic ballast (1), in particular for lamps.

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